Scanned focus deposition system

ABSTRACT

There is provided a deposition system ( 1 ) for yielding substantially uniform deposition of an evaporant material onto a substrate. The deposition system ( 1 ) comprises: a source ( 10 ) for generating a coherent energy beam; a substantially planar target ( 60 ) containing the evaporant material and disposed in spaced relation to the substrate; a focusing element ( 30 ) optically coupled to the source for focusing the coherent energy beam onto the target ( 60 ); and, an actuator ( 40 ) coupled to the focusing element ( 30 ) for reversibly translating the focusing element ( 30 ) along a scanning path directed substantially parallel to a target plane defined by the target ( 60 ). The focused coherent energy beam defines an impingement spot ( 14 ) on the target ( 60 ). The impingement spot ( 14 ) is displaced responsive to the translation of the focusing element ( 30 ) along the scanning path. The focus of the coherent energy beam on the target ( 60 ) thus remains substantially preserved.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The subject scanned focus deposition system is generally directedto a system for uniformly depositing an evaporant material onto asubstrate. More specifically, the scanned focus deposition system isdirected to a laser deposition system wherein the uniform deposition ofevaporant material from a target onto a substrate is facilitated byoptimally controlling the target material's consumption.

[0003] Generally in laser deposition techniques, an evaporant materialsource is excited by a coherent energy beam such that particles of theevaporant material are released from the source and deposited onto aproximally disposed substrate surface. In these deposition techniques,the evaporant source—or target—may be placed, along with a substrate,within a vacuum chamber. A pulsed laser beam generated by a sourcelocated outside the vacuum chamber is then directed by opticalcomponents into the vacuum chamber. The optical components include,among other things, a focusing element which focuses the laser beam toimpinge upon the target, defining an impingement spot. The concentratedenergy at the impingement spot causes the generation of a highlydirected evaporant plume that emanates from the target toward theproximally located substrate. The particles of target material containedin the evaporant plume then deposit onto the substrate's surface. Bysustaining this deposition process while the substrate is rotated orotherwise displaced in controlled manner, a coating of target materialmay be formed on the substrate.

[0004] In many applications of this technique, the uniformity ofdeposition is of paramount concern. Numerous factors bear on theuniformity that may ultimately be realized. Perhaps chief among them isthe degree to which the release of the target's evaporant material isregulated. The target includes a given mass of evaporant material which‘wears’ as the deposition process progresses. The progressive wear ofevaporant material potentially yields ruts and divots formed in thesurface of the target. Consequently, the regularity (concentration,direction of release, . . . ) with which particles of the evaporantmaterial are released from the target is quickly disrupted unlessadequate aversive measures are taken. There is, therefore, a need for adeposition system wherein such aversive measures are adequately taken tooptimize the uniformity of deposition that the system may realize.

[0005] 2. Prior Art

[0006] Deposition systems, including pulsed laser deposition systems,incorporating one or more aversive measures to minimize the detrimentaleffects of target wear are known in the art. The best prior art known toApplicant includes U.S. Pat. Nos. 5,654,975; 5,724,173; 5,606,449;5,661,290; 5,374,817; 5,144,120; 4,568,142; 4,504,110; 4,327,959;4,218,112; 3,642,343; and, 3,508,814.

[0007] One aversive measure incorporated in deposition systems known inthe art is to rotate the target about a rotation axis normal thereto.Another is to simultaneously scan the laser beam impinging upon thetarget along, for instance, the target's radial extent. A systememploying these measures is disclosed in U.S. Pat. No. 5,654,975entitled “SCANNING LASER BEAM DELIVERY SYSTEM,” and assigned to theAssignee of the present invention. In that system, a laser beam sourceand a beam transfer assembly cooperatively generate and direct anoptical path having a terminal segment that impinges upon a targetevaporant. An automatically controlled scanning mechanism displaces thebeam transfer assembly in appropriate manner to translate the terminalsegment of the optical beam path in a direction substantially normal tothe longitudinal direction along which it extends.

[0008] While this system yields marked improvement over prior artdeposition systems in the uniformity of deposition realized on asubstrate, a number of shortcomings yet prevail. First, the strictlateral translation of the optical beam path terminal segment does notnecessarily preserve the normal distance between the given focusingelement and the target surface. In typical deposition systems, theplanar front face of the target is not squarely oriented towards theincoming energy beam; for, the incident angle formed by the incomingbeam relative to the target's front face must be something other than90° if the resulting evaporant plume is to be directed towards the givensubstrate and not directly back towards the incoming energy beam,itself. Consequently, as the incoming beam is translated in a directionnormal to its propagating direction, the focusing element is displacedeither toward or away from that portion of the target's front facialplane on which it is to direct the energy beam. The beam's focus on thetarget is thus disturbed. That is, the effective shape and size of theimpingement spot which the incoming energy beam forms on the target at agiven instant in time is not preserved.

[0009] Another shortcoming prevails in the fact that the beam transferassembly comprising all the optical components for forming at least theterminal segment of the energy beam is displaced in its entirety toeffect the lateral translation of the beam path terminal segment. Thepractical inefficiencies inherent in such cumbersome manipulation ofcomponents are readily apparent.

SUMMARY OF THE INVENTION

[0010] Accordingly, it is an object of the present invention to effectsubstantially uniform deposition of evaporant material contained in atarget onto a substrate.

[0011] It is another object of the present invention to realizesubstantially uniform deposition of the target evaporant material onto asubstrate using a pulsed laser deposition technique.

[0012] It is another object of the present invention to optimallyregulate the consumption of the target evaporant material.

[0013] It is another object of the present invention to scan at leastthat portion of a coherent energy beam impinging upon the target in amanner that optimally preserves the beam's focus on the target.

[0014] It is yet another object of the present invention to effect thenecessary scanning of a coherent energy beam in a simple and efficientmanner.

[0015] It is still another object of the present invention to scan acoherent energy beam along the target by translating a focusing elementalong a scanning path that substantially preserves the beam's focus onthe target.

[0016] These and other objects are attained in the present inventionwhich provides a deposition system for substantially uniform depositionof an evaporant material onto a substrate. The deposition systemcomprises: a source for generating a coherent energy beam; asubstantially planar target containing the evaporant material which isdisposed in spaced relation to the substrate; a focusing elementoptically coupled to the source for focusing the coherent energy beamonto the target; and, an actuator coupled to the focusing element forreversibly translating that focusing element along a scanning pathdirected substantially parallel to a target plane defined by the target.The focused coherent energy beam defines an impingement spot on thetarget. The impingement spot is displaced responsive to the translationof the focusing element along the scanning path. The focus of thecoherent energy beam on the target thus remains substantially preserved.

[0017] While enhanced uniformity of deposition may be realized inaccordance with the present invention even without target rotation, thetarget is rotated in a preferred embodiment about a target rotation axissubstantially normal to the target plane. Also in that embodiment, theactuator is adapted to translate the focusing element in reciprocalmanner in accordance with a predetermined rate profile. The rate profileis defined based upon the position of the impingement spot relative tothe target rotation axis. Preferably, the rate profile is defined by asubstantially sinusoidal displacement profile, the rate of focusingelement translation being inversely related to the displacement of theimpingement spot from the target rotation axis.

[0018] In an alternate embodiment, the scanning path for the focusingelement is described by a plurality of directional components. Eachdirectional component in that embodiment is substantially parallel tothe target plane.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a perspective view, partially cut-away, of oneembodiment of the present invention in a typical application;

[0020]FIG. 2 is a detailed perspective view, partially cut-away, of aportion of the system shown in FIG. 1;

[0021]FIG. 3A is a schematic diagram illustrating an exemplarytranslation of the focusing element in an embodiment of the presentinvention;

[0022]FIG. 3B is a schematic diagram illustrating exemplary scan pathsas projected on a target plane that may be realized in accordance withthe present invention;

[0023]FIG. 3C is a graphic diagram illustrating exemplary displacementprofile curves pertaining to exemplary application of the presentinvention;

[0024]FIG. 4 is an illustrative diagram showing an alternate embodimentof a portion of the present invention;

[0025]FIG. 5A is another alternate embodiment of a portion of thepresent invention;

[0026]FIG. 5B is an illustrative diagram of yet another alternateembodiment of a portion of the present invention; and,

[0027]FIG. 5C is an illustrative diagram of still another alternateembodiment of a portion of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Turning now to FIG. 1, there is shown an exemplary arrangement ofcomponents for one embodiment of the invention. System 1 generallyincludes a source 10 for generating a coherent energy beam 12; afocusing element 30 for focusing beam 12 onto a target (not shown)contained within a vacuum chamber 50; and, an actuator 40 fortranslating along a scanning path indicated by the bi-directional arrow100. System 1 also includes an assembly 20 of components for guidingand/or delivering energy beam 12 to focusing element 30.

[0029] Component assembly 20 may include as many or as few components asare necessary for a given application. It may, for example, include afilter 22, a beam splitter or reflector 24, and an aperture element 26.These components 22, 24, 26, however, are shown only for exemplarypurposes, for assembly 20 may include any suitable components known inthe art. In certain applications where system requirements permit, itmay not even be necessary to employ assembly 20. In such applications,energy beam 12 would be delivered by the given source 10 directly tofocusing element 30.

[0030] Preferably, coherent energy beam 12 is a pulsed laser beam thatis generated by a pulsed laser source of any suitable type known in theart.

[0031] Focusing element 30 preferably includes a convex lens 31characterized by a finite focal distance. It may be embodied in any ofnumerous configurations and forms other than that shown. It isimportant, however, that the focusing portion—or lens 31 in theembodiment shown—possess sufficient radial or transaxial extent suchthat as it is scanned along the range of displacement described byscanning path 100, pulsed laser beam 12 remains fully directed throughits focusing portion.

[0032] Focusing element 30 is supported by such suitable means as a neck32 telescopically received within a base 33. Focusing element 30 isinitially positioned by its supporting structure at a sufficientdistance from the given target (not shown) that the length ofimpingement beam segment 12′ generated by its lens 31 preferablyapproaches, if not equals, the lens' characteristic focal distance.

[0033] Referring now to FIGS. 2-3B, impingement beam segment 12′ is thussubstantially focused onto the given target 60. Impingement beam segment12′ impinges upon the front surface of target 60 to define thereon (at agiven instant in time) an impingement spot 14 of a particular shape andsize. The focused energy at impingement spot 14 then causes an evaporantplume 61 to form and emanate therefrom. The particulate constituentsforming evaporant plume 61 are highly directed away from thesubstantially planar surface of target 60, toward an opposing substratefor deposition into/onto that substrate's surface (not shown).

[0034] The directivity of an evaporant plume 61 thus formed is very muchdependent upon the planar orientation of target 60. It is, therefore,necessary that a substantially planar target plane defined by thetarget's front surface (facing the incoming energy beam) be oriented atan angle other than 90° relative to the incoming impingement beamsegment 12′. Otherwise, the resulting evaporant plume 61 would besquarely directed back towards focusing element 30. Any attempt to placethe substrate in the path of the resulting plume 61 would then alsonecessarily place that substrate in the path of impingement beam segment12′, obstructing further operation. For this reason, target 60 isretained by a support mechanism 62 such that it defines a target planewhich forms an angle of 45°, or some other suitable value (in at leastone dimension), relative to the axis of the incoming impingement beamsegment 12′. This allows the substrate to be placed safely out of thepath of impingement beam segment 12′.

[0035] As the evaporant material that forms target 60 is consumed by theprocess of generating successive evaporant plumes 61, pits, ruts,divots, and other surface irregularities tend naturally to occur ontarget 60. As discussed in preceding paragraphs, such surfaceirregularities tend to disturb significantly enough the directivity ofsubsequently formed evaporant plumes 61 that acceptable levels ofdeposition uniformity become virtually impossible to attain.

[0036] One preventive measure typically taken is to minimize the dwelltime of impingement beam spot 14 on any particular portion of target 60by scanning that impingement spot 14 along, for instance, a direction200 as the target 60 itself is rotated by a predetermined angle ω abouta target rotation axis X (preferably defined along the normal to thetarget plane defined by target 60). This leads to a graduallyprogressing, generally even wear, or consumption, of target 60. This, inturn, leads to greater uniformity of deposition on the substrate.Ideally, the shape and size of impingement spot 14 is preserved, even asit travels through the range of displacements along an impingement spotscan path 200 between, preferably, a point at or near the rotation axisand a distal point 14′. That is, the focus of impingement beam 12′ ontarget 60 is substantially preserved despite the scanning.

[0037] In accordance with the present invention, this preservation offocus is simply yet precisely realized by translating focusing element30—or at least the focusing lens portion 31 of focusing element 30—alonga scanning path 100 directed substantially parallel to the target planedefined by the front surface of target 60. In the embodiment shown, thistranslation of focusing element 30 occurs only along the horizontaldimension. Note, however, that the translation may be along a compositescanning path having a non-zero component along both the horizontal andvertical dimensions, so long as the composite scanning path remains on aplane parallel to the target plane. Such an embodiment is indicated inFIG. 3B by the impingement spot scan path 200′ defining a range ofimpingement spot displacements from rotation axis X to a distal point14″.

[0038] While not shown in the Drawings, the composite scan path may incertain embodiments map a complex and irregular pattern, where theavailable resources and applicable requirements permit. Where aprogrammable controller(s) is available, for instance, optimal patternsof high complexity may be automatically generated and implemented in thescan, dynamically or otherwise.

[0039] Any suitable measures known in the art may be employed to effectthe necessary translation of focusing element 30 along the givenscanning path 100. In the exemplary embodiment of FIG. 1, thetranslation is effected automatically in reciprocal manner utilizing themechanism shown in greater detail in FIG. 2. Actuator 40 in thisembodiment includes a base 41 on which is disposed an elongate rail 43.A support block 42 is slidably engaged to rail 43 to be displaceablealong the actuating direction indicated by bi-directional arrow 100′.Preferably, actuating direction 100′ is parallel to the scanning path100.

[0040] Coupled to support block 42 is a suspension arm 34 extending fromthe focusing element's base 33. Suspension arm 34 is fixedly mounted tosupport block 42 by a suitable fastener 36 which may be released toadjust the position of suspension arm 34 relative to that support block42.

[0041] The displacement of support block 42 along rail 43 is controlledby a motor 44 or other comparable mechanism known in the art adapted togenerate the force required for the displacement. The force generated bymotor 44 is transferred to support block 42 via a substantially rigidtransfer link 45 extending between a pin member 46 anchored to supportblock 42 and a pin member 47 anchored to motor 44. Transfer link 45 iscoupled by suitable means to pin members 46, 47 in angularlydisplaceable manner.

[0042] During operation, then, motor 44 generates a displacement of pinmember 47. Responsive to this displacement, pin member 46 is caused viatransfer link 45 to undergo an accommodating displacement, which itimparts to support plate 42. The direction of displacement is limited toactuating direction 100′ by the engagement of support plate 42 with rail43. The displacement of support plate 42 over rail 43 yields thedisplacement of focusing element 30 along scanning path 100.

[0043] Referring again to FIG. 3B, the effective dwell time ofimpingement spot 14 at target rotation axis X cannot equal its effectivedwell time at, for instance, point 14′ on target 60 which is radiallyoffset from rotation axis X. Since target 60 is rotated about axis X,the instantaneous linear velocity at point 14′ on target 60 isnecessarily greater than the instantaneous linear velocity at a secondpoint on target 60 offset from target axis X by a lesser radialdistance. Consequently, the effective dwell time of impingement spot 14at point 14′, for instance, would invariably be less than the effectivedwell time of impingement spot 14 at or near target axis X—unless thescanning rate is accordingly controlled. Preferably, therefore, thetranslation of focusing element 30 along scanning path 100 is carriedout in accordance with a predetermined rate profile that is based uponthe displacement profile of the resulting impingement spot 14 relativeto target rotation axis X.

[0044] One such predetermined rate profile may be defined in accordancewith a substantially sinusoidal displacement profile, with the scanningrate being inversely related to the radial displacement of impingementspot 14 from the target rotation axis X. The scanning rate, inaccordance with that profile, is varied during a scan cycle to attain aminimum value at the radially outermost point(s) on target 60 reached byimpingement spot 14 during its displacement along scan path 200, and amaximum where impingement spot 14 is at its radially innermost pointalong that scan path 200. The alternate embodiment of actuator 40 shownin FIG. 4 represents one exemplary means by which such sinusoidalprofile may be effected. Note that scan path 200 may extendsubstantially across the diametric extent of target, traversing rotationaxis X.

[0045]FIG. 3C graphically illustrates examples of substantiallysinusoidal displacement profiles that may be employed in an exemplaryembodiment of the present invention. As there shown, the instantaneouslinear position of impingement spot 14 (in proportional units relativeto the target's rotation axis X) is plotted against the correspondinginstantaneous angle values within one complete cycle of the givenscanning action. Curve 210 simply represents, for referential purposes,the cosine curve defined by the angle values within the scan cycleshown. Similarly, curve 212 effectively represents the ideal case—thatis, where optimal target wear is realized given an infinitesimally smallimpingement spot 14 scanned through a path traversing the target'srotation axis X.

[0046] Curves 214 and 216 profile exemplary scanning actions that may beeffected in accordance with the present invention. With l denoting, forinstance, the length of transfer link 45 and r representing the radialdisplacement of pin member 47 from the central shaft (not shown) ofmotor 44, curve 214 represents the case where the ratio of l/r is ratherlow, equaling approximately 2 or so; whereas, curve 216 represents thecase where the l/r ratio is relatively high, equaling approximately 8 orso. Note that the higher l/r ratio of curve 216 causes it to moreclosely follow the reference cosine curve 210.

[0047] Among other things, it is graphically apparent from these curvesthat the instantaneous rate at which scanning occurs varies from aminimum value at the points of maximum linear displacement (from thetarget's rotation axis X) to a maximum value at the target's rotationaxis X (where linear position equals 0). Given a motor 44 operating at afixed frequency (at a fixed rpm), the angle values denotinginstantaneous angular displacement positions within a motor shaftrevolution would map linearly to a time reference. The instantaneousslope of each curve 214, 216, which reaches a minimum at the givencurve's amplitude extremes, is therefore indicative of (for instance,proportional to) the instantaneous scan rate.

[0048] Referring next to FIG. 4, there is illustrated an alternateembodiment 140 of the translation actuator. In this embodiment, actuator140 includes a motor 141 that drives an axial shaft 142 to which aplatform member 143 is coupled. A pin member 144 extends from platformmember 143, and a transfer link 145 couples pin member 144 to a pinmember 146 extending from support block 142 (whose details, for the sakeof clarity, are not shown). Where transfer link 145 is substantiallyrigid, suitable accommodating measures must be taken such as therotatable coupling of pin members 144, 146 respectively to platformmember 143 and support block 42—or, alternatively, the angularlydisplaceable coupling of transfer link 145 to pin members 144 and 146.The embodiment shown, however, permits transfer link 145 to be formedfrom a flexible material, thus obviating these accommodating measures.

[0049] Actuator 140, in this embodiment, further includes a tensionspring member 147 which extends between a pin member 148 affixed tosupport block 142 and a stationary pin member 149 affixed to base 41(not shown) or some other fixed platform/surface. Spring member 147possesses the properties sufficient for it to expand as the motor-drivenrotation of platform member 143 indicated by the directional arrow 105pulls transfer link 145 taut and, thereby, pulls support platform 142along translation path 100′. During those phases of the platformmember's rotation wherein pin member 144 is drawn towards pin member 146(to relax the tension on transfer link 145), the tension of springmember 147 draws support block 142 in the opposing direction alongtranslation path 100′. Spring member 147 thus serves to bias supportblock 42 towards stationary pin member 149. Reciprocal translation ofsupport block 42 in either direction along path 100′ may then occur evenwith motor 141 driving the translation in only one direction.

[0050] Actuator 140 may, if necessary, further include a verticalactuator component 150 coupled to a base 151 of focusing element 30 insuch manner that vertical displacement of focusing element 30 may beeffected concurrently with the horizontal translation thereof. When thuscombined with the horizontal translation, the concurrent displacement offocusing element 30 indicated by the directional arrows 110 and 100′would, depending on the control employed, enable any of numerouseffective beam scan paths to be described on the given target plane. Incertain embodiments, vertical actuator component 150 may be programmable(as may the unshown control for motor 141).

[0051] Pertinent portions of another alternate embodiment 240 of thetranslation actuator are shown in FIG. 5A. In this embodiment, thespring or other resilient element 147 and flexible translation link 145are removed in favor of a transfer link 245 formed as a substantiallyrigid elongate arm member. Arm member 245 is coupled in angularlydisplaceable manner to a pin member 244 extending from platform member243 and to a pin member 246 extending from support block 42. Theangularly displaceable coupling may be realized through any suitablemeans, such as a ball bearing joint 247, 248. The reciprocatingtranslation 42 is then fully driven by the rotation of platform member243.

[0052] Yet another embodiment 340 of the translation mechanism is shownin FIG. 5B. As there shown, actuator 340, in this embodiment, employs aplatform member 343 shaped with a predetermined peripheral contour.Platform member 343 is rotatably driven by a motor 341 via a drive shaft342. The driven movement of platform member 343 is transferred tosupport block 42 by a substantially rigid transfer link member 345 thatprojects from a pin member 346 extending from support block 42 andengages the platform member's sidewall portion 343 a. At the opposingend of support block 42 is coupled a spring or other resilient member347 of suitable properties which biases support block 42 away from astationary member 349 affixed to either base 41 (not shown) or otherstationary platform/surface.

[0053] As platform member 343 in the given configuration is driven torotate, the biasing force of spring member 347 maintains the abuttingengagement of the platform member's sidewall portion 343 a and transferlink 345. Consequently, the nature and extent of the support block'stranslation along the directions 100′ are determined by the contourdescribed by the platform member's sidewall portion 343 a. That is, r(θ)is proportional to the instantaneous scanning rate, where parameters rand θ respectively represent the instantaneous distance from the axis ofthe platform's rotation to a point along the platform's peripheraloutline and the instantaneous angular offset of a given radial extentfrom an angular reference.

[0054] Pertinent portions of still another alternate embodiment 440 ofthe translation actuator is shown in FIG. 5C. Actuator 440 enables theadjustable re-configuration thereof necessary to vary the range oftranslation of support block 42 along path 100′. Actuator 440 includes aplatform member 443 a to which an adjustment member 443 b is slidablycoupled for adjustable displacement. Adjustment member 443 b may thus bepositioned on platform member 443 a at any point along the range ofdisplacement indicated by the bi-directional arrow 115. A securingmember 443 c is provided to releasably lock member 443 b at a selectedposition.

[0055] Actuator 440 further includes a pin member 444 coupled securelyto adjustment member 443 b. The adjustable displacement of adjustmentmember 443 b enables pin member 444 to be radially offset from the axisof the drive shaft 443 extending from the given motor 441. Since thedriving force generated by motor 441 is transferred to support platform42 via a transfer link 445 engaging pin member 444, the degree ofmovement transferred by actuator 440 is thus rendered selectivelyadjustable.

[0056] Note that this embodiment 440 of the translation actuator may beemployed in combination with other features employed in a number of thepreceding embodiments. Note also that by utilizing other suitablemeasures (not shown), the offset displacement of member 443 b relativeto platform member 443 a may be controlled dynamically in furtherembodiments. Variability of the pin member 444 radial offset (along path115) from the axis of drive shaft 442 could then be effected within agiven drive cycle of motor 441. This would permit great flexibility incustomizing the system's scan profile.

[0057] Although this invention has been described in connection withspecific forms and embodiments thereof, it will be appreciated thatvarious modifications other than those discussed above may be resortedto without departing from the spirit or scope of the invention. Forexample, equivalent elements may be substituted for those specificallyshown and described, and certain features may be used independently ofother features, all without departing from the spirit or scope of theinvention as defined in the appended Claims.

What is claimed is:
 1. A deposition system for substantially uniformdeposition of an evaporant material onto a substrate comprising: (a) asource for generating a coherent energy beam; (b) a substantially planartarget disposed in spaced relation to the substrate and defining atarget plane, said target containing the evaporant material; (c) afocusing element optically coupled to said source for focusing saidcoherent energy beam onto said target, said focused coherent energy beamdefining an impingement spot on said target; and, (d) an actuatorcoupled to said focusing element for reversibly translating saidfocusing element along a scanning path directed substantially parallelto said target plane for displacing said impingement spot; whereby saidfocus of said coherent energy beam on said target remains substantiallypreserved.
 2. The deposition system as recited in claim 1 wherein saidtarget is rotated about a target rotation axis substantially normal tosaid target plane.
 3. The deposition system as recited in claim 2wherein said actuator is adapted to automatically translate saidfocusing element in reciprocal manner.
 4. The deposition system asrecited in claim 3 wherein said actuator is adapted to translate saidfocusing element in accordance with a predetermined rate profile basedupon the position of said impingement spot relative to said targetrotation axis.
 5. The deposition system as recited in claim 4 whereinsaid predetermined rate profile is defined by a substantially sinusoidaldisplacement profile, the rate of said translation being inverselyrelated to the displacement of said impingement spot from said targetrotation axis.
 6. The deposition system as recited in claim 1 whereinsaid focusing element includes a convex lens.
 7. The deposition systemas recited in claim 1 wherein said scanning path is described by aplurality of directional components, each said directional componentbeing substantially parallel to said target plane.
 8. The depositionsystem as recited in claim 7 further comprising a vertical actuatorcoupled to said focusing element.
 9. The deposition system as recited inclaim 4 wherein said actuator includes an angularly displaceableplatform member having a sidewall portion defining therefor apredetermined peripheral contour.
 10. The deposition system as recitedin claim 4 wherein said actuator includes: (a) an angularly displaceableplatform member; and, (b) an adjustment member coupled to said platformmember in selectively displaceable manner.
 11. A reciprocated focusingsystem for pulsed laser deposition of a target evaporant material onto asubstrate comprising: (a) a source for generating a laser beam; (b) asubstantially planar target disposed in spaced relation to the substrateand defining a target plane, said target containing the evaporantmaterial; (c) a focusing element optically coupled to said source forfocusing said laser beam onto said target, said focused laser beamdefining an impingement spot on said target; and, (d) an actuatorcoupled to said focusing element for reciprocally translating saidfocusing element along a scanning path to displace said impingementspot, said scanning path being described by at least one directionalcomponent, each said directional component of said scanning path beingsubstantially parallel to said target plane; whereby said focus of saidlaser beam on said target remains substantially preserved during saiddisplacement of said impingement spot along said target.
 12. Thereciprocated focusing system as recited in claim 11 wherein said targetis rotated about a target rotation axis substantially normal to saidtarget plane.
 13. The reciprocated focusing system as recited in claim12 wherein said actuator is adapted to translate said focusing elementin accordance with a predetermined rate profile based upon the positionof said impingement spot relative to said target rotation axis.
 14. Thereciprocated focusing system as recited in claim 13 wherein saidpredetermined rate profile is defined by a substantially sinusoidaldisplacement profile, the rate of said translation being inverselyrelated to the displacement of said impingement spot from said targetrotation axis.
 15. The reciprocated focusing system as recited in claim11 wherein said scanning path is described by a plurality of saiddirectional components.
 16. The reciprocated focusing system as recitedin claim 15 wherein said actuator includes at least first and secondactuator components for respectively translating said impingement spotalong said directional compnents.
 17. The reciprocated focusing systemas recited in claim 16 wherein at least one of said first and secondactuator components is programmable.
 18. A pulsed laser depositionsystem for substantially uniform deposition of an evaporant materialonto a substrate comprising: (a) a source for generating a laser beam;(b) a substantially planar target disposed in spaced relation to thesubstrate and defining a target plane, said target containing theevaporant material; (c) a focusing element optically coupled to saidsource for focusing said laser beam onto said target, said focused laserbeam defining on said target an impingement spot having a predeterminedshape and a predetermined size dimension; and, (d) an actuator coupledto said focusing element for reversibly translating said focusingelement along a scanning path described by at least one directionalcomponent parallel to said target plane; whereby said impingement spotis scanned along said target, said predetermined shape and sizedimension of said impingement spot on said target being substantiallypreserved during said scanning.
 19. The pulsed laser deposition systemas recited in claim 18 wherein said target is rotated about a targetrotation axis substantially normal to said target plane.
 20. The pulsedlaser deposition system as recited in claim 19 wherein said actuator isadapted to automatically translate said focusing element in reciprocolmanner.
 21. The pulsed laser deposition system as recited in claim 20wherein said actuator is adapted to translate said focusing element inaccordance with a predetermined rate profile based upon the position ofsaid impingement spot relative to said target rotation axis.
 22. Thepulsed laser deposition system as recited in claim 21 wherein the rateof said translation is inversely related to the displacement of saidimpingement spot from said target rotation axis.
 23. The pulsed laserdeposition system as recited in claim 22 wherein said scanning path iscompositely described by a plurality of said directional components.